Semiconductor light-emitting devices including light emitting diodes (LEDs), resonant cavity light emitting diodes (RCLEDs), vertical cavity laser diodes (VCSELs), and edge emitting lasers are among the most efficient light sources currently available. Materials systems currently of interest in the manufacture of high-brightness light emitting devices capable of operation across the visible spectrum include Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. Typically, III-nitride light emitting devices are fabricated by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a sapphire, silicon carbide, III-nitride, or other suitable substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. The stack often includes one or more n-type layers doped with, for example, Si, formed over the substrate, one or more light emitting layers in an active region formed over the n-type layer or layers, and one or more p-type layers doped with, for example, Mg, formed over the active region. Electrical contacts are formed on the n- and p-type regions.
FIG. 1 illustrates a device described in more detail in U.S. Pat. No. 7,009,213 which is incorporated herein by reference. A light emitter 4 is located in a recess 38 in a surface 22 of an optical element 2 to which light emitter 4 is bonded. The optical element 2 is directly bonded to light emitter 4. Light emitter 4 includes a stack of semiconductor layers and an active region, capable of emitting light. The stack of semiconductor layers is attached to a transparent superstrate 34 formed from a material such as, for example, sapphire, SiC, GaN, AlN, or GaP. Light emitter 4 includes a first semiconductor layer 8 of n-type conductivity and a second semiconductor layer 10 of p-type conductivity. Semiconductor layers 8 and 10 are electrically coupled to active region 12. Active region 12 is, for example, a p-n diode junction associated with the interface of layers 8 and 10. Alternatively, active region 12 includes one or more semiconductor layers that are doped n-type or p-type or are undoped. Active region 12 can also include quantum wells. N-contact 14 and p-contact 16 are electrically coupled to semiconductor layers 8 and 10, respectively. Active region 12 emits light upon application of a suitable voltage across contacts 14 and 16. Optical element 2 is bounded by surface 24. The shape of surface 24 reduces the reflection of light emitted by light emitter 4.